1. Field of the Invention
The present invention relates generally to the fields of enzymology and carbohydrate chemistry. More specifically, the present invention relates to purified, homogeneous porcine kidney L-fucokinase and uses thereof.
2. Description of the Related Art
L-Fucose (6-deoxy-L-galactose) is an important sugar in animal cells since it is involved in various recognition reactions of glycoproteins and glycolipids (1). Thus, oligosaccharides that have .alpha.1,2-linked L-fucose are precursors for blood group A and B antigens (2). In the Lewis blood group antigens, Gal.beta.1,3 (Fuc.alpha.1,4) GlcNAc-R and Fuc.alpha.1,2Gal.beta.1,3(Fuc.alpha.1,4)GlcNAc-R are determinants for Lewis.sup.a and Lewis.sup.b blood group antigens. In addition, fucosylated and sialylated oligosaccharides have been found to be the recognition molecules for the E- and P-selectins, two members of the selectin family of cell adhesion molecules (3). These selectins and their fucosylated- (and sialylated) ligands are important in inflammation and in the recognition of leukocytes for endothelial cells (4).
The primary pathway for the formation of L-fucose in procaryotic and eucaryotic cells is from D-mannose via an internal oxidation-reduction of GDP-D-mannose and this product is epimerized to produce GDP-L-fucose (5-8). However, studies in rats showed that radiolabeled L-fucose could be incorporated into glycoproteins (9,10), suggesting an alternate route for activation of L-fucose. An L-fucokinase that synthesizes .beta.-L-fucose-1-phosphate (11), and a GDP-L-fucose pyrophosphorylase (12) were partially purified from pig liver. However, the fucokinase preparation had rather broad substrate specificity with regard to sugar and nucleoside triphosphate, probably because of contaminating enzymes, such as hexokinase in the partially purified fraction.
The prior art is deficient in the lack of purified pig kidney fucokinase. The present invention fulfills this longstanding need and desire in the art.